ABC | Volume 112, Nº3, March 2019

Original Article Kiyose et al A systematic review for valvular prostheses Arq Bras Cardiol. 2019; 112(3):292-301 Figure 2 – Forest plot showing the effects of biological versus mechanical prostheses on mortality. 14.4% 5.0% 26.6% 46.0% 23.2% 0.9% 21.2% 45.3% 8.7% 8.7% 0.96 [0.80, 1.15] 1.13 [0.81, 1.58] 1.20 [1.07, 1.34] 1.10 [0.94, 1.28] 1.05 [0.92, 1.20] 0.83 [0.37, 1.84] 0.98 [0.85, 1.12] 1.01 [0.92, 1.11] 100.0% 1.07 [0.99, 1.15] 1.16 [0.91, 1.49] 1.16 [0.91, 1.49] 1.1.1 Aortic valve Edinburgh 2003 Stassano 2009 Veterans Affairs 2000 Subtotal (95 CI) Test for overall effect: Z = 1.17 (p = 0.24) Heterogeneity: Tau 2 = 0.01; Chi 2 = 4.09, df = 2 (p = 0.13); I 2 = 51% 1.1.2 Mitral valve Edinburgh 2003 Vallejo 1981 Veterans Affairs 2000 Subtotal (95 CI) Test for overall effect: Z = 0.26 (p = 0.79) Heterogeneity: Tau 2 = 0.00; Chi 2 = 0.85, df = 2 (p = 0.65); I 2 = 0% 1.1.3 Mitral + aortic valve Edinburgh 2003 Subtotal (95 CI) Test for overall effect: Z = 1.21 (p = 0.23) Heterogeneity: Not applicable Total (95 CI) Test for overall effect: Z = 1.67 (p = 0.10) Test for subgroup differences: Chi 2 = 1.55, df = 2 (p = 0.46); I 2 = 0% Heterogeneity: Tau 2 = 0.00; Chi 2 = 7.73, df = 6 (p = 0.26); I 2 = 22% 0.1 0.2 0.5 1 2 5 10 Favours biological Favours mechanical Study or Subgroup Weight Risk Ratio Risk Ratio IV, Random, 95% CI IV, Random, 95% CI Table 2 – Risk of bias in included studies Vallejo 1981 Veterans 2000 Edinburgh 2003 Stassano 2009 Random sequence generation Unclear Unclear Unclear Unclear Allocation concealment Low risk of bias Low risk of bias Low risk of bias Low risk of bias Blinding of outcome assessors Low risk of bias Low risk of bias Low risk of bias Low risk of bias Complete outcome data Low risk of bias Low risk of bias Low risk of bias Low risk of bias Currently, the decision between a biological and mechanical prosthesis is based on medical assessment and patient preference. The following are important factors in this decision: biological and chronological age, life expectancy, and absolute or relative contraindications to the use of oral anticoagulants after surgery, e.g., comorbidities or intense sport activity. The 2014 American Guidelines 22 recommend a mechanical prosthesis for mitral or aortic valve implantation in patients less than 60 years old who have no contraindication to the use of oral anticoagulants (recommendation IIa, evidence level B); a bioprosthesis is recommended for those aged over 70 years, and biological or mechanical prostheses are recommended for patients between 60 and 70 years of age (both with recommendation IIa and evidence level B). 22 The 2012 European directive recommends the use of a mechanical prosthesis in patients less than 60 years old in the aortic position and in those under 65 in the mitral position (recommendation IIa, evidence level C). 23 Therefore, there is currently no exact recommendation for the choice of prosthesis in the 60-70 year age range, and there is no solid evidence upon which the choice of one prosthesis over another can be made. Thus, variability in preferences will likely occur among patients, in special for those aged between 60 and 70 years, and the data from this systematic review should be useful to inform the decision. 24 Randomized studies to assess treatments for valvular heart disease pose unique clinical challenges in cardiology for several reasons. First, the disease is of relatively low prevalence. Second, comparing surgical complex interventions in randomized controlled trials is difficult. Third, important clinical endpoints are assessed only after decades of follow-up. Fourth, continuing advances in prosthetic heart valve technology make follow-up a moving target because long-term data by definition are available only for older prostheses. Newer tissue and mechanical prostheses afford superior hemodynamics compared with their older counterparts, and data suggest that durability and patient mortality are superior with newer compared with older bioprostheses. In parallel, the mechanical prosthesis has also evolved. Nevertheless, important advances have been made through the results of randomized trials in equally challenging fields in cardiology, for instance, assessment of CABG vs medical treatment or percutaneous treatment. It is in the public interest, both in health and financial terms, 296